Electronically controlled automatic transmission

Abstract

An electronically controlled automatic transmission including an automatic gear shift for changing the gear ratio according to the coupling/decoupling of the brake and clutch, a hydraulic switch for controlling a hydraulic pressure exerted on the brake and clutch, a timer for setting a time of coupling/decoupling of the clutch and brake during a shifting period, a detector for detecting vehicle information, a time correcting device for correcting the set time according to the detected vehicle information, and an electronic control device for driving the hydraulic switch and for changing the state of coupling/decoupling. The electronic control device having a temperature detector for detecting the temperature of the working fluid of the hydraulic switch, and a feedback stop device for stopping the correction by the time correcting device when the temperature detector detects that the temperature of the working fluid is below a predetermined temperature.

What is claimed is: 
     
       1. An electronically controlled automatic transmission for a vehicle comprising: automatic gear shift means, having a clutch and a brake driven by hydraulic pressure, for changing the gear ratio in accordance with the coupling/decoupling of said clutch and brake;   hydraulic switching means for controlling the hydraulic pressure exerted on said clutch and brake;   timing means for setting during a shifting period a coupling/decoupling time of said clutch and brake;   vehicle information detecting means for detecting, during the shifting period, vehicle information;   time correction means for correcting the time set by said timing means in accordance with vehicle information from said vehicle information detecting means;   electronic control means for driving said hydraulic pressure switching means in accordance with said corrected set time, and for changing the state of coupling and decoupling of said clutch and brake; temperature detecting means for detecting the temperature of a working fluid of said hydraulic pressure switching means; and feedback stop means for stopping, when said temperature detecting means detects that the temperature of the working fluid is below a predetermined temperature, the correction of the set time of coupling/releasing by said time correction means.   
     
     
       2. The electronically controlled automatic transmission as claimed in claim 1, wherein said time correction means provides a corrected time which is the time from the moment of shifting to the moment when one of the clutch and brake is released. 
     
     
       3. The electronically controlled automatic transmission as claimed in claim 1, wherein said electronic control means is operable for indicating the coupling of one of the clutch and the brake at a coupling side thereof, and wherein said correction means provides a correction time which is the time used for coupling when one of the clutch and brake is coupled. 
     
     
       4. An electronically controlled automatic transmission for a vehicle comprising: automatic gear shift means, having a clutch and a brake driven by hydraulic pressure, for changing the gear ratio in accordance with the coupling and decoupling of said clutch and brake;   hydraulic switching means for controlling the hydraulic pressure exerted on said clutch and brake;   rate setting means for setting a rate of coupling/releasing of said clutch and brake during a shifting period;   vehicle information detecting means for detecting vehicle information during the shifting period;   rate correction means for correcting the rate of coupling/releasing by said rate setting means in accordance with vehicle information from said vehicle information detecting means; and   electronic control means for driving said hydraulic pressure switching means in accordance with said correction set rate, and for changing the state of coupling and decoupling of said clutch and brake; a temperature detecting means for detecting the temperature of a working fluid of said hydraulic pressure switching means; and feedback stop means for stopping, when said temperature detecting means detects that the temperature of the working fluid is below a predetermined temperature, the correction of the rate set by said rate correction means.   
     
     
       5. The electronically controlled automatic transmission as claimed in claim 4, wherein said electronic control means is operable for indicating the coupling of one of said clutch and brake at a coupling side thereof, and said corrected set rate is the rate used for determining the speed for coupling when one of the clutch and said brake is coupled.